Nanocrystalline silicon quantum dots within an oxide layer

US6774061B2 · kind B2 · utility

Assignee

• STMicroelectronics SA

Inventors

• Salvatore Coffa · Milano, IT
• Davide Giuseppe Patti · Mascalucia, IT

Key dates

• Filing date: Mar 15, 2001
• Grant date: Aug 10, 2004
• Expiry date: May 26, 2021

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S438/962

Abstract

A process for forming a thin layer of Silicon nanocrystals in an oxide layer is disclosed. The process includes, on a semiconductive substrate, thermally oxidizing a first portion of the substrate into an oxide layer, forming Silicon ions within the layer of oxide, and thermally treating the Silicon ions to become the thin layer of Silicon nanocrystals. In the inventive process the formation of the Silicon ions is by ionic implantation of the Silicon ions into the oxide at an ionization energy of between 0.1 keV and 7 keV, and preferably between 1 and 5 keV. This allows the Silicon atoms to coalesce in a lower temperature than would otherwise be possible. Additionally, more than one layer of nanocrystals can be formed by performing more than one implantation at more than one energy level. Embodiments of the invention can be used to form non-volatile memory devices with a very high quality having a very small size.